iscsi tools: set non negotiated params early.

This patch has the iscsi tools pass down the non-negotiated
iscsi settings before doing iscsi login. This allows the
drivers to get info that might be neede to setup the session
early.

This patch also adds the missing discovery_sess param to
the non negotiated params.

Acked-by: Lee Duncan <lduncan@suse.com>
Added an upstream patch from Mike Christie (bnc#869356)